Britain must be prepared to reinforce Gibraltar with warships ahead of Brexit negotiations in a bid to ward off Spanish designs on the Mediterranean colony, according to one adviser.

In an article on the ConservativeHome website published Tuesday, Ministry of Defence (MoD) adviser and director of the Allison Center for Foreign Policy Studies at the Heritage Foundation Luke Coffey said the UK must be prepared to defend ‘the Rock’.

“The Ministry of Defence should also make a grand gesture by increasing the Royal Navy’s visible presence in Gibraltar,” he wrote.

His comments come after Spanish Foreign Minister Jose Manuel Garcia-Margallo called for a joint sovereignty treaty in the wake of the Brexit vote in June.

Coffey said Gibraltarians must be supported if they become isolated, including by air if required.